PROJECT SUMMARY There is an urgent need to provide diagnoses for the approximately ~30 million Americans with undiagnosed disease. With the vast majority (85%) of undiagnosed diseases believed to have underlying genetic causes, the utilization of whole exome sequencing (WES), and to a lesser extent whole genome sequencing (WGS), has resulted in diagnosis rates of 25-40%, as reported in the prior literature. In Phase I of the Undiagnosed Diseases Network (UDN), the Duke/Columbia clinical site has capitalized upon both of these technologies, as well as deep phenotyping and innovative bioinformatics, to achieve an overall diagnosis rate of ~50%, and a diagnostic rate of ~40% for the most challenging cases: patients with prior negative WES results. The site's findings from Phase I of the UDN also demonstrated that undiagnosed patients/parents of undiagnosed children experience chaos and parents of children with undiagnosed diseases have high rates of anxiety and depression. This led to the development of a survey to measure patients' and parents' expectations and utilization of genome sequencing results. Beyond this, the team has contributed to UDN policies, established successful collaborations, and been active in key network leadership positions. With an already established infrastructure and successful outcomes, the Duke/Columbia site is well positioned to continue this work for the next four years and to sustain it beyond. The Specific Aims of this proposal are as follows: Specific Aim 1: Comprehensively evaluate 30 patients annually with undiagnosed diseases. We will capitalize on our site's diagnostic specialty strengths, to evaluate patients in any specialty, adult and pediatric, within the one-week timeframe, use phenotypic data to aid genome interpretations, and effectively communicate results to patients and their families with genetic counseling. Specific Aim 2: Analyze the WES and WGS of patients to provide diagnoses and use RNA-sequencing as an adjunct when WES/WGS do not provide a diagnosis. Specific Aim 3: Prospectively examine psychosocial characteristics associated with being undiagnosed (Aim 3A) and expectations and utilization of genomic sequencing results (Aim 3B). Specific Aim 4: Contribute to activities of the UDN to foster a collaborative and sustainable network. The Duke/Columbia clinical site has all the capabilities required to be a successful clinical site in Phase II of the UDN, contributing to achieve the network's goal of evaluating patients with undiagnosed diseases and ultimately improve the health and well- being of these individuals and their families.